Convergence Video
Video Encoders/Decoders
Single-Chip Video Decoder
CX25836/7
High Performance in a Small Package
Conexants broadband communications portfolio includes a comprehensive
suite of semiconductor solutions that enable the digital home and information
network. The CX25836/7 is Conexants fourth-generation video decoding
solution. It provides a highly integrated single-chip analog video capture
solution ideal for a wide range of digital video systems applications.
The CX25836/7 features, although applicable to a wide range of analog video
applications, are focused on both the security and consumer electronics
markets. Most notably, CX25836s fast camera locking capabilities and flexible
programmable inputs make it most suitable for the security camera market.
The CX25837, with its ability to decode Composite Video Baseband Signal
(CVBS), S-Video, and YPbPr, is best suited to address the wide array
of consumer electronics requirements. Both devices are distinguished by high
quality, flexibility, integration, and ease of use. Both fit into a wide array of
Distinguishing Features
applications: set-top-boxes, flat panel displays (such as LCD and Plasma TVs),
Integrated NTSC/PAL/SECAM
HDTVs, and PVRs/DVRs.
video decoding
High Quality
Auto detection and configuration
The CX25836/7 integrates two high-performance 10-bit ADCs and provides a
for video
full 10-bit data path through the video decoder to maintain optimum end-to-
Two 10 bit A/D
end video quality. Eight video inputs provide flexible analog muxing that can
be configured for any of the following:
YPbPr component video input
Ease of Use
Eight CVBS inputs
Four Y/C inputs
12mm X 12mm 80-pin TQFP
Three composite with one Y/C and one YPbPr
One composite with two Y/C and one YPbPr 7mm X 7mm 64-pin TQFP
Two composite with two YPbPr (CX25837 only)
CCIR 656/601/VIP
The CX25837 uses its high quality Analog-to-Digital Converter (ADC) to Integrated anti-alias lter
sample the YPbPr video format, which is most often found on prosumer
On-chip voltage regulator
(intermediate to advanced end user) type equipment. Simultaneous
digitization of Pb and Pr, through the 10-bit chrominance A/D, is used to
offer this feature cost effectively yet yield the highest quality.
Part Number CX25836/7
Description Single-Chip Video DecoderConvergence Video
Video Encoders/Decoders
Integrated Filters
Flexible Architecture
All video inputs have integrated anti-alias filters, eliminating the
With eight programmable input ports and a configurable output
need for external filter components. These filters help improve the
port for 4:2:2 digital, the CX25836/7 can be used to capture
video decoding process by removing aliasing artifacts prior to the
video from TV tuners, DVD players, video cameras, VCRs, game
digitization process.
consoles, or any other sources of composite Y/C or component
(480i) video. The CX25836/7 video inputs can be programmed
Conexant also employs a proprietary method of luma/chroma
for up to eight video sources; a maximum of eight CVBS input
separation of the composite video sources. Conceptually similar
channels. Each of these inputs can be used to support CVBS,
to a 4H adaptive chrominance comb filter used for NTSC and
S-Video, or component video inputs. The total number and
PAL, Conexant performs a slight twist to provide unparalleled
configuration of video inputs is user-defined.
performance. Through the use of adaptive correlation logic, the
resulting combed image provides improved performance over
Ease of Use
a standard 4H comb solution. In the case where no correlation
The CX25836/7 requires minimal programming for startup. These
exists between lines, the decoder automatically falls back to the
devices are preconfigured in a default mode for development,
chrominance band-pass and luma notch filter.
verification, and fast prototyping. Additionally, the CX25836/7 can
auto detect all worldwide broadcast video standards.
In the case of SECAM, a bell filter is implemented. The net effect
of the various filtering stages results in a high-quality image with
Internally, the CX25836/7 uses on-chip logic to determine
reduced cross-chrominance and cross-luminance artifacts (such
which video standard is present and reconfigures automatically
as dot crawl, hanging dots, rainbow effects) and thus restores full
so no user intervention is necessary. This is especially useful
bandwidth to luminance data from composite sources.
in geographic regions where different video standards may
be received on a channel-by-channel basis. However, like the
operation of traditional video decoders where the user chooses a
specific video standard, the automatic detection feature may be
turned off.
XTI
Master
PIXCLK
Clock
XTO
Video
VID_DATA[7:0]
Input
Output
VBI Data Slicer and Decoder
VRESET/PRGM3
Port:
HRESET/PRGM2
BT.656,
CVBS1/Y1
FIELD/PRGM1
BT.601,
VIP 2.0 DVALID/PRGM0
CVBS2/Y2
10-Bit
IR_RX/PRGM5
CVBS/
CVBS3/Y3 I/O Pin
Video
IR_TX/PRGM6
LUMA
MUX
Decoder - Arbitrary
ADC
NTSC, PAL, Horizontal
SER_CLK/HAD[0]
2-Wire
SECAM and Vertical
CVBS4/Y4/SIF1/Pb
SER_DATA/HAD[1]
Serial
with 4H Multi-tap
Command
Adaptive Polyphase
CVBS5/C1/SIF2/Pb
CHIP_SEL/VIPCLK
or
10-Bit Comb Scaler
CVBS6/C2/SIF3/Pb VIP Host HCTL/PRGM3
Filter
Chroma/
I/F
Sound IF IRQ_N/PRGM4
ADC
CVBS7/C3/SIF4/Pr
Audio Over -
Sample or
PLL_CLK/PRGM7
CVBS8/C4/SIF5/Pr
Generic Clock
CX25836/7 System Block Diagram
Input MUX, Anti-alias Filter and AGC